Its really simple... you obviously are using some type of router to share your connection. Your router creates its own personal ip addresses for your network. These are private addresses that only work in your network.
Firstly, you need to go into you router configuration screen and enable "port forwarding" or "add hosted program"... it will be different based on your brand... but its somthing like that. Make sure port 80 is forwarded to your computer... or you add webserver to the list of hosted programs... however your router handles it.
Next you need to know that anyone inside your network has to access your website via your network ip NOT YOUR PUBLIC IP.
Now if you want somone outside your network to view it you need to send them your public IP address. www.whatismyip.com will show that to you. You will not be able to access your website via your public IP address.... strange but thats the way it goes :-p
That should get you going
